The present invention relates to a synchronous yarn feeding device for a textile machine.
As is known in the art, yarn is delivered by means of a yarn feeding drum and a driving belt. FIG. 11 illustrates a typical conventional yarn feeding device. The drum 1 having a plurality of round bars 3 formed with a cage-shaped periphery is rotatably mounted on a yarn guide frame 5. A belt 2 presses the yarn 9 onto the smooth outer periphery of the drum, thereby continuing the yarn feeding operation by frictional force. On frame 5 a pair of porcelain eyes 8 are mounted for guiding the incoming yarn and the outgoing yarn, respectively. Eyes 8 guide the incoming yarn F or outgoing yarn under pressure of belt 2 so that the yarn can be fed on or off the drum.
A drawback of prior art yarn feeding apparatus is that instability and inaccuracies may be introduced into the yarn feeding operation. As the amount of yarn fed on the drum is increased, the contact surface between the belt and the drum is decreased and the contact surface becomes irregular. Therefore, the driving belt 2 will have a different effect on the speed of the turning drum for each drum that it is in contact with. Moreover, these differences are not easily perceived by the operator, and thus cannot be corrected by adjusting any conventional means. The quality of weaved cloth is therefore degraded. Yarn breakage is increased and the profitability of production is decreased.